"We can't afford many mistakes now or we'll compromise what we've built these last few weeks."

First half goals from Edinson Cavani and Marek Hamsik did the damage as Napoli showed they are past the blip that recently saw them lose three in a row and fail to win in five.

They almost got off to a flying start in the derby of the Two Sicilies as Gokhan Inler thudded the post with a rising shot from outside the box.

But goalkeeper Morgan De Sanctis had to come to their rescue moments later with two quick-fire saves, first with his knees from Josip Ilicic and then at full-stretch from Abel Hernandez's header.

However, Milan Milanovic inadvertently handled Goran Pandev's cross, the ball rebounding off his thigh onto his arm, and the referee pointed to the spot.

Palermo complained bitterly but Milanovic's arm clearly prevented the ball from going into the danger area and Cavani improved his poor penalty record this season -- he has missed five out of nine -- with the goal from the spot on 16 minutes.

Ilicic produced a moment of magic to skip away from Salvatore Aronica but Paolo Cannavaro came quickly across to snuff out the danger.

But Napoli doubled their advantage when Pandev's great vision released Hamsik to prod home from 15 yards.

Cavani could have had a second but failed to hit the target when escaping alone after the break.

Roma's hopes of qualifying for the Champions League next season all but mathematically died following a 0-0 draw at Chievo in sopping wet conditions in Verona.

Roma trail Napoli by six points with just two games left, giving them little realistic hope of closing that gap.

And in fairness they were lucky to come away from Verona with a point in a match made hugely difficult by wet conditions that affected the way the ball rolled and bounced.

Roma coach Luis Enrique couldn't hide his frustration.

"That wasn't a match it was water-polo," he complained.

"A point is useless to us. We needed to win but it was difficult on this pitch.

"This hasn't been a happy year, I don't know what will happen in the future but a coach has to accept criticism: it's the results that judge a coach.

"Several times we've had the possibility of going third but we've not done well."

Chievo had much the better of the chances and Roma barely troubled home goalkeeper Stefano Sorrentino.

American international Michael Bradley put Alberto Paloschi in behind the Roma backline but Gianluca Curci saved his left-footed shot.

Finland midfielder Perparim Hetemaj was then put clean through by Rinaldo Cruzado. He tried to dink the ball over Curci but the pitch contributed in him failing to get the ball off the ground and the goalkeeper saved easily.